I am not opening a political debate, so lets not go there, but I would like to offer a hypothesis and invite your opinions.

My best friend is a gun dealer. He and I have worked several gun shows together--mostly when my tables were right next to his.
A universal truth in the gun business is that Democrats sell guns. When liberals are in power at the federal level, guns fly off the shelves. During the Obama administration, my buddy did very well selling guns while I struggled to sell my knives. Shortly after Trump was elected, I had my best show ever and he couldn't sell guns at cost.

Theory:
When gun people feel like they may loose the opportunity to by guns, they use all of their disposable income to do so--leaving precious little money left over for anything that wouldn't be included on a ban list. Hence, only guns and certain accessories sell at gun shows when a liberal government is seated.
Conversely, when a conservative sits in the oval office, there is no rush to spend your hard earned greenbacks on expensive guns because there is no fear of them being banned. BUT, gun people still like guns, and they enjoy the gun show environment, so they still go to them. Having spent $10 to get in, they want to buy something worthy so they don't leave empty-handed. Maybe one of those fancy knives they saw and admired (but didn't buy) back when they felt compelled to throw all their money at ARs and AKs.
As the next election nears, the pendulum will surely swing again, so our windows for successful showings at gun shows may be narrow.

I haven't seen that much correlation with my sales here in the SE. My sales fluctuations are more closely related to the general economy (which is also greatly affected by party in power). However, I do not do gun shows anymore and there in may be the difference. Back when I did a few gun shows I did find it cyclic, but wasn't paying attention. My few ventures into gun shows was sporadic so you really may be on point Andy.